jQuery.ajax(): A listing of allowed values for property contentType, other than default ?

jQuery.ajax(): A listing of allowed values for property contentType, other than default ?

Hi
 
For jQuery.ajax(), is there a listing of the allowed values that can be assigned to property contentType that it can process?
 
I am performing jQuery.ajax() with the following property settings: type is "post" and dataType is "json" .
 
Property contentType's default value is: " application/x-www-form-urlencoded; charset=UTF-8" , and if I assign the same default value to this property, then jQuery.ajax() works fine and creates a well-formed POST request body.
 
However, if I use "application/json; charset=UTF-8" , the jQuery.ajax() aborts without any useful error message, just "error", and fails to create a POST request body but creates instead a malformed OPTIONS request body.
 
Note: This issue only occurs on Mozilla Firefox and Google Chrome, not IE9.
  1. $.ajax({
        url: url,
        type: "post",
        dataType: "json",
        contentType: 'application/json',
        data: data,
        success: successCallback,
        error: errorCallback,
        complete: completeCallback
        });








 
So, is there an acceptable list of contentType values that jQuery.ajax() will allow?
 
Thanks
 
Jeff in Seattle